1. Field of the Invention
The present invention relates to a technique for retaining the heat of a sensor part of an optically pumped magnetometer.
2. Background Art
In order to increase alkali metal atoms in a vapor cell which are excited by irradiation light applied to the cell, it is necessary to increase the gas density of the alkali metal in the cell by heating the cell. In order to retain the heat of the cell, there are techniques using hot air or heaters.
Appl. Phys. B76, 325-328 (2003) discloses that a cell is housed in a plastic coiled tube and the heat of the cell is retained by applying hot air to the inside of the tube using a hot air generator.
APPLIED PHYSICS LETTERS 85, 6409 (2004) discloses that transparent film heaters are provided to the parts through which irradiation light applied to a cell passes, and the heat of the cell is retained by applying current to the transparent film heater.
APPLIED PHYSICS LETTERS 89, 134105 (2006) discloses that hot air is applied to the inside of an oven housing a cell using a hot air generator to fill that container with hot air, thereby retaining the heat of the cell.
REVIEW OF SCIENCE INSTRUMENTS 77, 113106 (2006) discloses that hot air is applied using a hot air generator to the inside of a magnetic shielding provided to suppress environmental magnetic noise coming into a cell to fill the magnetic shielding with hot air, thereby retaining the heat of the cell.
JP Patent Publication (Kokai) No. 2001-339302A discloses that a c-field control circuit and a heater coil control-equipped temperature control circuit are prepared and a c-field coil wound on a cavity housing a cell is used as a heater by means of a coil function switch device, thereby retaining the heat of the cell.
JP Patent Publication (Kokai) No. 2002-344314A discloses that a film heater is provided to a c-field coil wound on a cavity housing a cell, or a cell, and current is applied to the film heater, thereby retaining the heat of the cell.
JP Patent Publication (Kokai) No. 2003-229766A discloses that a cell is housed in a metal case provided with a heater, and current is applied to the heater, thereby retaining the heat of the cell.